Four 14-year-old boys have been arrested after a gas canister was thrown at a Premier League team bus.
The coach, carrying the Aston Villa squad, was hit following a match against Burnley on 27 August.
The canister, which caused around £10,000 damage, struck the windscreen as the coach entered the M65 at junction 10.
The teenagers have been held on suspicion of criminal damage with intent to endanger life.
Nobody was injured in the incident, but Lancashire Police said it could have caused a serious crash.
PC Ross Bosdorff said officers had taken the incident "extremely seriously".